Film forming apparatus

Abstract

A film forming apparatus includes a cylindrical evaporation source, an electrode, and a gas passage. The evaporation source is composed of metal and includes an internal space for accommodating a workplace. The electrode is arranged in the internal space of the evaporation source, The gas passage supplies gas to the internal space of the evaporation source from a space outside the evaporation source. The gas passage includes an end portion located in the internal space. The end portion of the gas passage includes a first section composed of a first material and a second section composed of a second material. The first material and the second material have different thermal expansion coefficients.

The invention claimed is: 
     
       1. A film forming apparatus comprising:
 a cylindrical evaporation source that is composed of metal and includes an internal space for accommodating a workpiece; 
 an electrode arranged in the internal space of the evaporation source; and 
 a gas passage that supplies gas to the internal space of the evaporation source from a space outside the evaporation source and includes an end portion located in the internal space, wherein 
 the film forming apparatus is configured to form a film by depositing, on the workpiece, metal ions are released from the evaporation source by arc discharge generated between the evaporation source and the electrode, 
 the end portion of the gas passage includes
 a first section composed of a first material, and 
 a second section composed of a second material, and 
 
 the first material and the second material have different thermal expansion coefficients. 
 
     
     
       2. The film forming apparatus according to  claim 1 , further comprising an adhesion-preventing member that is arranged between the evaporation source and the electrode and is electrically insulated from the evaporation source and the electrode, wherein
 the electrode includes the first section, 
 the adhesion-preventing member includes the second section, and 
 the end portion of the gas passage is constituted by the electrode and the adhesion-preventing member. 
 
     
     
       3. The film forming apparatus according to  claim 2 , wherein the first material, of which the electrode is composed, has a higher thermal conduction coefficient than that of the second material, of which the adhesion-preventing member is composed. 
     
     
       4. The film forming apparatus according to  claim 2 , wherein the first material, of which the electrode is composed, has a lower thermal expansion coefficient than that of the second material, of which the adhesion-preventing member is composed. 
     
     
       5. The film forming apparatus according to  claim 1 , wherein the first material, of which the electrode is composed, has a lower thermal expansion coefficient than that of the second material, of which the adhesion-preventing member is composed.